Apparatus for heating liquid to high temperature



Nov. 18, 1958 E. DURHAM APPARATUS FOR HEATING LIQUID TO HIGH TEMPERATURE Filed Nov. 15, 1955 IN VEN TOR.

Edwin Durham BY ATTORNEY United States Patent Ofiice se m Patented Nov. 18, 1958 APPARATUS FOR HEATING LIQUID TO HIGH TEMPERATURE Edwin Durham, Westlield, J., assignor to The Babcock & Wilcox Company, New York, N. Y., a corporation of New Jersey The present invention relates to a high temperature liquid heater, and more particularly to apparatus for heating water to a high temperature and pressure.

High temperature hot water is particularly useful for space heating purposes, and is also useful for process purposes, while temperatures of the order of 300 to 400 F. are desirable. The water is usually heated by the products of fuel combustion in a heater where the liquid is passed through the heating surfaces under forced flow conditions produced by a circulation pump.

In accordance with the present invention, I provide a liquid heater where both forced flow and natural flow of liquid through the heater is utilized. The heater is particularly characterized by a lo-w.first cost and low maintenance while attaining a high heat exchange efliciency with outstanding reliability. of operation. These advantageous characteristics are obtained by a novel constructional relationship of the heater parts wherein the incoming liquid to be heated is initially passed through a plurality of tubular heating elements positioned in a high temperature zone where a high degree of radiant heating efiect is obtained. Thereafter the liquid is heated by predominantly convection heating effects and the liquid is finally again passed through a high heat exchange zone prior to its discharge from the heater.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodiment of the invention.

Of the drawings:

Fig. 1 is an elevation, in section, of a liquid heater constructed and arranged in accordance with the present invention; and

Fig. 2 is a plan section taken on the line.22 of Fig. 1.

In general, as shown in the drawings, the present invention is illustrated as applied in the heating of high temperature water for space heating purposes. The furnace is of generally rectangular horizontal and vertical cross section, and is horizontally elongated with water heating tubes forming a part of substantially all of the heater walls, except the fioor of the unit. 1

Referring to Figs. 1 and 2, the heating unit is provided with a front wall 11 which is of refractory construction in its lower portion and is provided with one or more port openings 12 for an oil burner 13. The heating unit may be fired by gaseous fuels without substantial change in the heater. Solid fuels may be utilized with minor changes in the unit floor construction to accommodate a stoker. The upper portion of the front wall 11 is pro vided with tube and refractory construction where the tubes 14 open to an exteriorly disposed transverse inlet header 15. From the header 15 the tubes 14 extend upwardly along the upper portion of the front wall 11 and are bent to extend ina horizontal direction across the roof 16 of the heating unit 10. In the rearward portion of the heating unit, the tubes 14 are bent in a downward direction to form a part of the rear wall 17 and open into a transversely positioned lower header 18 disa posed in the lower portion of the rear wall 17.

The rear wall transverseheader 18 is closed at its opposite ends and provided with horizontally projecting stub headers 20 and 21, each of which opens to one end of the header 18 and having its centerline substantially normal to and intersecting the centerline of the header 18. The assembly of headers 18, 2t and 21 is positioned between transversely spaced longitudinally extending horizontally positioned lower headers 22 and 23 which project along the side walls of the unit to a position beyond the front wall 11. A pair of horizontally extending longi-. tudinal upper, headers 24 corresponding in general as to cross-section and length with the lower longitudinal headers 22 and 23 are positioned at a level immediately above the roof 16 of the unit. The longitudinally extending upper and lower headers are provided with substantially upright corner tubes 25 and 26 positioned on the exterior ofthe front wall 11. As shown in Fig. 1, the corner tube 25 connects the lower header 23 with the upper header 24, while a similar corner tube 26 connects the lower header 22 with its corresponding upper header (not shown). The inlet header 15 is closed at the opposite ends but mechanically connected to the corner tubes 25 and 26, as for example by welding, to form a strong structural assembly.

The stub headers 20 and 21 are each connected to a separate row of tubes 27 which is formed into a sinuous configuration so that the tubes project transversely across the space between the side walls of theunit in a plurality of return bends and open at their upper ends into the rearward portion of the upper longitudinal headers. The upper headers are each provided with a transverse diaphragm 29 positioned adjacent the forward tube of the row of tubes 27 and forming a chamber 28 in the rearward portion of the upper longitudinal headers. The chambers 28 are each provided with a row of tubes 30 which is substantially vertical, and connects the upper and lower headers along the marginal side walls of the unit. Thus, the water delivered to the transverse header 18 passes into the stub headers 20 and 21 and upwardly through the sinuous tubes 27 into the upper longitudinal headers and returns to the lower longitudinal headers 22 and 23 through a row of tubes 30 in each wall of the unit. Thereafter, the water discharges forwardly along the lower longitudinal headers to be distributed in its flow in an upper direction through side wall and division wall tubes.

A row of substantially upright tubes 31 connects the lower longitudinal header 23 with the upper header .24.

The heated liquid delivered to the upper longitudinal headers'is discharged to a horizontally disposed header 35 which is transversely positioned above the roof 16 intermediate the longitudinal length of thesetting. The header 35 is provided with an outlet duct 36 positioned centrally *of the header, and is directly connected with the upper longitudinal headers by an offset fitting 37 positioned at the opposite ends of the header 35 (see Fig. 1). In addition, the header 35 is provided with a plurality of feeder connection pipes 38 opening to longitudinally spaced positions along the upper headers (see the Fig. 1

' connectionsbetween the headers 24 and 35).

A lower transverse header 40 is disposed between the lower longitudinal headers 22 and 23 and is in liquid flow relationship therewith. The header 40 is provided with an upwardly extending row of tubes 41 which extend transversely across the unit to form a division wall inter mediate the length of the unit. At their upper end portions the tubes 41 are alternately bent out of the plane of the tube row to form spaced rows of widely spaced tubes 41a and 41b which open into the header 35. The lower portion of the row of tubes 41 is provided with studs Welded thereto to form a generally gas tight batile, while the intertube spaces between the tube rows'41a and 41b are open to form a gas pass 42. In addition to the upright row of tubes 41 extending upwardly from the lower header 40, a pair of spaced rows of tubes 43 and 44 are extended rearwardly and u-pwardy to a position iongitudinally spaced rearwardly of the tube row 41 where the tube rows are combined in the same plane to extend in a substantially upright direction to open into the header 35. The tube rows 43 and 44 are provided with suitable studs welded thereto to form a generally gas tight bafile 45 which extends upwardly from a position spaced above the floor 46 of the unit to the roof 16. The intertube spaces between the tubes 43 and 44 are open to provide a gas pass 47 between the lower end of the bafiie 45 and the floor 46. The refractory materials and the fiat studs on the tubes 14 in the upper rear portion of the heater setting is omitted to provide a gas outlet 48.

With the construction described the space in the forward portion of the unit, between the front wall 11 and the tubes 41 forms a combustion space 50 with the gases produced therein passing through the opening 42 to a substantially unobstructed down-flow gas pass 51 formed be tween the row of tubes 41 and the baffle 45. The heating gases leave the gas pass 51 through the lower gas opening 47 to pass upwardly between the baffle 45 and the rear wall 17 to the gas outlet 48. pass 52 the heating gases are in convection heat exchange contact with the sinuous tubes 27 positioned therein.

In the operation of the apparatus described, the liquid to be heated is delivered to the header under a positive pressure from a heating system circulating pump, or if so desired, from a pump intended to cause circulation of liquid through the heating unit alone. The liquid is forced through the tubes 16 to the lower rear header 18, with the relatively cool liquid effectively cooling the roof 16 of the setting. From the header 18 the liquid is passed through the stub headers and 21 and thence through the convection tubes 27 to the chambers 28. The partially heated liquid passes downwardly through the convection gas-pass tubes into the lower headers 22 and 23 for upward flow through the wall tubes 31, 33 and the division wall tubes 41, 43 and 44. The flow circuit of liquid through the tubes to the upper headers 24 and thence to the transverse header is largely of the forced I flow type supplemented by some natural circulation through the tubes, including flow through the unheated corner tubes 25 and 26. Advantageously the entire unit may be assembled in the shops, shipped to ,the' sitefor erection, and installed as a complete unit with a minimum of installation costs, The tube and header'construction ofthe unit is self supporting and does not necessitate the use of external structural materials to support the unit.

While in accordance with the provisions of the statutes,

'1 have illustrated and described herein the best form and mode of operation of the invention now known to me, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed withoutdeparting from the spirit of the invention covered by my claims, and that certain features of my invention may sometimes be used to advantage without a corresponding use of otherfeatures.

What is claimed is: f i r 1, A high temperature liquid heater comprising walls defining a heating unit, wall means separating the interior In passing through the up-.

of said heating unit into a combustion chamber and a gas pass connected for serial flow of heating gases thereupper portion of the front wall and the roof of said heating unit connected to said inlet header and said lower rear header, a bank of convection heating tubes positioned in said gas pass of said heating unit, means for passing liquid from said lower rear header through said bankof convection tubes, upper and lower headers horizontally disposed longitudinally of said heating unit along the side edges thereof, means for discharging liquid from said bank of convection tubes to said lower longitudinally disposed side headers, substantially upright tubes in the Walls of said heating unit connecting said upper and lower longitudinally disposed side headers, and means for collecting the heated liquid from said upper headers for discharge from said heating unit including a transverse header directly connected with said upper headers and positioned above the roof of said heating unit.

2. A high temperature liquid heater comprising walls defining a heating unit, wall means separating the interior of said heating unit into a combustion chamber and multiple gas passes connected for serial flow of heating gases therethrough, a liquid inlet header positioned on the exterior side of the front wall of said heating unit, a horizontally disposed lower header positioned adjacent the rear wall of said heating unit, liquid cooled tubes extending along the interior surface of the roof of said heating unit connected to said inlet header and said lower rear header, stub headers opening to said lower rear header and extending forwardly along the sides of said heating unit through the rearmost of said multiple gas passes, a bank of convection heating tubes opening to each of said stub headers and positioned in the rearmost gas pass of said heating unit, means for passing liquid from said stub headers through said bank of convection tubes, upper and lower header horizontally disposed longitudinally of said heating unit along the side edges thereof, means for discharging liquid fro-m said bank of convection tubes to said lower longitudinally disposed side headers, substantially upr'ight tubes in the walls of said heating unit connecting said upper and lower longitudinally disposed side headers, and means.

for collecting the heated liquid from said upper headers for discharge from said heating unit including. a transverse header directly connected with said upper headers.

and positioned above the roof of said heating'unit.

3. A high temperature liquid heater comprising walls defining a heating unit, wall means separating the interior of said heating unit into a combustion chamber and multiple gas passes connected for serial flow of heating gases therethrough, a liquid inlet header positioned on the exterior side of the front wall of said heating unit, a horizontally disposed lower header positioned adjacent the rear wall of said heating unit, liquid cooled tubes extending along the' interior surface of the roof and the rear Wall of said heating unit and connecting said inlet header with said lower rear header, a bank of convection heating tubes positioned in the rearward portion of said heating unit, means for passing liquid from said lower rearheader through said bank of convection tubes, upper and lower headers horizontally disposedlongitudinally of said heating unit along the edges thereof, means for discharging liquid from said bank of convection tubes to said lower longitudinally disposed headers, substantially upright tubes in the walls of said heating unit connecting said upper and lower longitudinally disposed headers, means for collecting the heated liquid from said upper headers for dis-charge from' said heating unit including a transverse header directlyconnected with said upper headers and positioned above the roof of said heating unit, a lower transverse header connecting the lower headers intermediate the longitudinal length of said heating unit, and rows of upwardly extending tubes connecting said lower transverse header with said upper transverse header and positioned in the said wall means separating said heating unit into the combustion chamber and multiple gas passes.

4. A high temperature liquid heater comprising walls defining a heating unit, wall means separating the interior of said heating unit into a combustion chamber and multiple gas passes connected for serial flow of heating gases therethrough, a liquid inlet header positioned on the exterior side of the front wall of said heating unit, a horizontally disposed lower header positioned adjacent the lower edge of the' rear wall of said heating unit, liquid cooled tubes extending along the interior surface of the roof and the rear wall of said heating unit and connecting said inlet header with said lower rear header, stub headers opening to said lower rear header and extending forwardly along the sides of said heating unit through the rearmost of said multiple gas passes, upper and lower headers horizontally disposed longitudinally of said heating unit along the edges thereof, said lower longitudinally disposed headers extending rearwardly in parallel with said stub headers, the upper headers having a diaphragm therein positioned adjacent the separat ing wall means of said rearmost gas pass, a bank of convection heating tubes positioned in the rearmost gas pass of said heating unit, means for passing liquid from said lower rear header through said bank of convection tubes to said upper header, means for discharging liquid from the rear portion of said upper header to said lower longitudinally disposed headers, substantially upright tubes in the walls of said heating unit connecting said upper and lower longitudinally disposed headers, and means for collecting the heated liquid from said upper headers for discharge from said heating unit including a transverse header directly connected with said upper headers and positioned above the roof of said heating unit.

References Cited in the file of this patent UNITED STATES PATENTS 1,973,377 Gordon Sept. 11, 1934 2,142,612 Lucke Jan. 3, 1939 FOREIGN PATENTS 721,838 Germany June 19, 1942 

